The invention relates to an apparatus for handling sheet-like conveyable articles, it also being possible for such conveyable articles to comprise folded sheets or stapled articles or the like, which are to be transported, for example, from a magazine to a conveying chain and are set down on the conveying chain.
Known gripper arms can be pivoted about a pivot axis, which is located at a sufficient distance above the plane of the transporting chain and/or of the plane of the sheet-like articles which are to be conveyed, from a receiving position into a discharging position. Located at the bottom end of the gripper arms in each case are gripper tongs with mutually opposite gripper claws which are prestressed into the closed position by spring means and of which generally one is connected pivotably to the gripper arm and is opened and closed by an actuating linkage both in the receiving position and in the discharging position, in order, in the receiving position, to grip a leading border of a conveyable article and, in the discharging position, to release the conveyable article again.
An actuating linkage between a framework-mounted cam plate, a cam follower, which is in contact with the latter, and the pivotable gripper claw serves for opening the gripper tongs in time with the pivoting movements of the gripper arm at least in the receiving position of the same. In the case of the known gripper-arm designs, said actuating mechanism involves comparatively high outlay and requires, for the cam-plate drive, a framework-mounted drive shaft guided parallel to the pivot axis of the gripper arm.
FR-A-705 283 discloses an apparatus for handling sheet-like conveyable articles which contains a pivotably mounted gripper arm which can be pivoted back and forth by means of a crank drive. Gripper tongs with a pair of gripper claws are located at the free, bottom end of the gripper arm. One of the gripper claws can be opened and closed by means of an actuating linkage likewise arranged on the gripper arm. Moreover, the gripper tongs can be pivoted in their entirety, by means of a further actuating linkage, relative to the gripper arm in order to produce a certain movement path of the gripper claws during pivoting of the gripper arm. This pivoting of the gripper tongs in their entirety is achieved in that a cam plate, which is seated on the crankshaft for the drive of the gripper arm, subjects the further actuating linkage, which is assigned to the gripper tongs and contains a cam follower, to an adjustment movement. The actuating linkage serving for pivoting the gripper tongs in their entirety acts on the gripper tongs not directly, but, on the one hand, via a directing guide, which is framework-mounted in a pivotable manner, and, on the other hand, via a follower-roller lever connected to the gripper tongs.
FR-A-2 254 435 discloses a further apparatus for handling sheet-like conveyable articles by way of a pivotably mounted gripper arm which is made to pivot by means of a connecting rod. Gripper tongs, located at the free end of the gripper arm, contain a pair of gripper claws, of which one, for opening and closing the gripper tongs, is mounted pivotably at the free gripper-arm end and is provided with a follower-roller lever which interacts with a directing guide, which is framework-mounted in a pivotable manner. Certain movements of the directing guide are produced, via a cam-plate follower of the directing guide, by means of a cam plate which circulates synchronously with a rotary drive for actuating the connecting rod acting on the gripper arm.
The invention is intended to achieve the object of configuring an apparatus for handling sheet-like conveyable articles having the features of the preamble of conveyable articles having the features of the preamble of Patent claim 1 such that the actuating mechanism for opening and closing the gripper tongs is rendered considerably simpler and less expensive, in particular a smaller number of components, in relation to known designs, being used without high precision of the gripper operation having to be dispensed with.
This object is achieved by the characterizing features of Patent claim 1. Advantageous configurations and developments form the subject matter of the patent claims subordinate to claim 1.
The idea on which the invention is based consists in the drive mechanism for producing the pivoting movements or the gripper arm itself, or of the gripper arms themselves, also being used for actuating the respective gripper claw, for which purpose the cam for the cam follower of the actuating linkage of the pivotable gripper claw is joined directly to the drive crank for the gripper-arm-pivoting connecting rod or to said connecting rod. This is because it has been found that, precisely at the point when the gripper arm reaches, as it were, the respective dead-centre positions, both the drive crank and the connecting rod of the pivot-arm drive execute comparatively rapid rotary movements or pivoting movements which are suitable for deriving the opening movement of the gripper tongs in the receiving position and the discharging position.
According to one embodiment, the actuating linkage for opening and closing the pivotable gripper claw contains a lever which is mounted on the gripper arm and to which one end of a coupling rod is connected, of which the other end is connected to the pivotable gripper claw, and on which , furthermore, the cam follower is located, the latter expediently being designed as a roller which is in contact with the cam.
It should be mentioned in this context that the cam follower or the follower roller do not, of course, have to be in contact with the directing curve of the cam throughout the entire movement sequence of said cam. Rather, the pivotable gripper claw is kept in the closed position by spring prestressing and is only moved into the open position by virtue of the cam follower running onto regions of the cam in the receiving position and/or the discharging position of the pivot arm.